U.S. patent application number 11/329527 was filed with the patent office on 2006-08-10 for method to establish and organize an ad-hoc wireless peer to peer network.
Invention is credited to Shengwei Cai, Wai Chen, Jasmine Chennikara-Varghese, Toshiro Hikita, John Lee, Marcus Pang.
Application Number | 20060176847 11/329527 |
Document ID | / |
Family ID | 36678132 |
Filed Date | 2006-08-10 |
United States Patent
Application |
20060176847 |
Kind Code |
A1 |
Chen; Wai ; et al. |
August 10, 2006 |
Method to establish and organize an ad-hoc wireless peer to peer
network
Abstract
A method for organizing and maintaining an ad-hoc network for
communication between a plurality of moving devices is disclosed.
The method comprises the steps of grouping the plurality of moving
devices into at least one local peer group (LPG), ordering the
plurality of devices within each LPG based upon a relative position
of each of the plurality of devices within each LPG and assigning a
unique identifier for each of the plurality of moving devices,
where the unique identifier is based, in part on the LPG that the
corresponding moving device is located.
Inventors: |
Chen; Wai; (Parsippany,
NJ) ; Chennikara-Varghese; Jasmine; (Somerset,
NJ) ; Pang; Marcus; (Manalapan, NJ) ; Hikita;
Toshiro; (Fort Lee, NJ) ; Lee; John; (Howell,
NJ) ; Cai; Shengwei; (Florham Park, NJ) |
Correspondence
Address: |
TELCORDIA TECHNOLOGIES, INC.
ONE TELCORDIA DRIVE 5G116
PISCATAWAY
NJ
08854-4157
US
|
Family ID: |
36678132 |
Appl. No.: |
11/329527 |
Filed: |
January 11, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60643373 |
Jan 11, 2005 |
|
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|
Current U.S.
Class: |
370/328 |
Current CPC
Class: |
H04L 29/12009 20130101;
H04L 29/12216 20130101; H04W 64/00 20130101; H04W 4/08 20130101;
H04W 84/18 20130101; H04L 29/12801 20130101; H04L 61/6004 20130101;
H04W 92/18 20130101; G08G 1/161 20130101; H04W 8/26 20130101; H04L
61/2007 20130101 |
Class at
Publication: |
370/328 |
International
Class: |
H04Q 7/00 20060101
H04Q007/00 |
Claims
1. A method for organizing and maintaining an ad-hoc network for
communication between a plurality of moving devices comprising the
steps of: (a) grouping said plurality of moving devices into at
least one local peer group (LPG); (b) ordering said plurality of
moving devices within each LPG based upon a relative position of
each of said plurality of devices within each LPG; and (c)
assigning a unique identifier for each of said plurality of moving
devices, where said unique identifier is based, in part on the LPG
in which the corresponding moving device is located.
2. The method of claim 1, wherein step b includes reordering said
plurality of moving devices based upon a change in the relative
position of the plurality of moving devices which is caused by
motion of said plurality of moving devices.
3. The method of claim 1, wherein step c includes modifying said
unique identifier for a moving device when said moving device
changes LPGs.
4. The method of claim 1, wherein a message is routed within an LPG
based upon the ordering of the plurality of moving devices and
further based upon a type of communication message.
5. The method of claim 1, wherein said unique identifier is an IP
address.
6. The method of claim 5, wherein step c includes assigning two IP
addresses when a moving device is located near a border of two
adjacent LPGs or within an overlapping area of said adjacent LPGs
to allow for communication between the adjacent LPGs.
7. The method of claim 1, wherein at least one LPG is a stationary
LPG, said at least one stationary LPG has a fixed location that is
predefined.
8. The method of claim 1, wherein said LPG is at least one dynamic
LPG, said dynamic LPG is formed based upon a clustering of one or
more of said plurality of moving devices.
9. The method of claim 1, wherein said LPGs are divided into
equivalent cells (EC) defined by a group of moving devices that are
within a one hop of each other such that only one transmission of a
message is needed to reach any of the group of moving devices
within the EC, said EC is controlled by an equivalent cell header
(ECH).
10. The method of claim 1, wherein step b comprises the step of:
creating a position vector representing the relative position of
each moving device within each LPG.
11. The method of claim 5, wherein said IP address is assigned
based upon a predefined network prefix concatenated with a unique
LPG identification and a unique moving device identification.
12. The method of claim 11, wherein said unique LPG identification
and said unique moving device identification are calculated from a
hash function.
13. The method of claim 11, wherein said unique LPG identification
and said unique moving device identification are provided from an
external wireless device in communication with the plurality of
moving devices.
14. The method of claim 1, wherein the step b comprises the steps
of: broadcasting a message including a first moving device's
position, an indication of an intended message direction, and a
time of the broadcast; receiving said broadcast message by a second
moving device; estimating a displacement of said first moving
device based upon said received broadcast message; calculating a
current position for said first moving device based upon said
estimated displacement and said first moving device's position; and
comparing said calculated current position with a position of said
second moving device.
15. The method of claim 10, wherein the step of creating a position
vector comprises the steps of: initializing the position vector;
broadcasting said initialized position vector to another moving
device that is joining the LPG; comparing, by said another moving
device, its position with position information that is included in
said broadcast; inserting a position value of said another moving
device into said position vector based upon the comparison; and
broadcasting an updated position vector to all other moving devices
within the LPG.
16. The method of claim 15, wherein upon receipt of said updated
position vector at least one of said other moving devices modify
its position in the updated position vector based upon its change
in relative position.
17. The method of claim 14, wherein said second moving device will
relay the message when the second moving device is determined to be
along the intended message direction.
18. The method of claim 1, wherein each of said plurality of moving
devices are classified according to a type of moving device and
said unique identifier is assigned based upon said classification.
Description
RELATED APPLICATIONS
[0001] This application is related to and claims the benefit of
U.S. Provisional Application No. 60/643,373 filed on Jan. 11,
2005.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] This invention relates to an ad-hoc wireless network for a
communication in a mobile environment. More specifically, the
invention relates to the establishment and maintenance of a
moving-device to moving-device ad-hoc wireless network to achieve
near-instantaneous communications.
[0004] 2. Description of Related Art
[0005] Wireless technology has become common in all aspects of life
today, whether it be a wireless home or office network, so-called
"hotspot" networks at local cafes, fast food chains or hotels, or
even citywide implementations of WiFi technologies. The aim of this
wireless push in society is to provide accessibility to information
and to increase the productivity that society as a whole has
enjoyed through the wide acceptance and utilization of computer
networks and especially the Internet. Wireless networking
technology, such as 802.11a/b/g, allows WiFi-enabled devices to
connect to each other as they would in a standard wired network
without the restriction of wires. People are given the freedom to
remain connected to a network regardless of their physical location
within the network coverage area.
[0006] With this goal in mind, several cities have attempted to
create a wireless network for the city. For example, on Jul. 29,
2004, Grand Haven, Mich. claimed the distinction of being the
"first WiFi city in America" with its implementation of a citywide
wireless network covering the 6 square miles of the city and
extending 15 miles into Lake Michigan. Many city officials see WiFi
as an infrastructure necessity, much like sewage, power, telephone
and transportation, for attracting and retaining business. The
benefits of such systems for the city administrators are many,
ranging from providing communication among city employees to
providing public service announcements, advisories and other useful
information to the citizenry at large.
[0007] In this drive for greater wireless connectivity, one area of
everyday life has lagged behind. The roads and highways of America
have remained largely untouched by wireless technology beyond
rudimentary satellite and cellular phone systems. However, there
are many advantages to be gained from wireless network technology
implementations on American roads. Among the most notable are
traffic advisories, Amber alerts, weather advisories, etc., which
could be relayed to all vehicles that may be affected on an
immediate basis.
[0008] Further, networking automobiles together allows the relay of
information about a vehicle that may affect other vehicles in the
vicinity. For example, an automobile may suddenly brake; this
action could be reported to all vehicles behind the braking
automobile instantaneously, thus allowing the drivers of the other
vehicles to take necessary action with less urgency. This aspect
has clear implications for reducing traffic accidents and
congestion. This type of wireless networking may appear in many
aspects of vehicle safety applications, including, but not limited
to, urgent road obstacle warning, intersection coordination, hidden
driveway warning, lane-change or merging assistance.
[0009] Vehicle safety communications ("VSC") may be broadly
categorized into vehicle-to-vehicle and vehicle-with-infrastructure
communications. In vehicle-to-vehicle communication, vehicles
communicate with each other without support from a stationary
infrastructure. Vehicles communicate with each other when they are
within the same radio range of each other or when multiple-hop
relay via other vehicles is possible. In
vehicle-with-infrastructure communication, vehicles communicate
with each other with the support of infrastructure such as roadside
wireless access points. In this case, vehicles may also communicate
with the infrastructure only.
[0010] Key VSC performance requirements include low latency (on the
order of 100 mili-seconds) and sustained throughput (or
equivalently, the percentage of neighboring vehicles that
successfully receive warning messages) in order to support various
VSC applications such as collision avoidance.
[0011] Simply installing wireless antenna on a moving vehicle and
then transmitting uncoordinated communications would not suffice
for satisfying these requirements. Specifically, by transmitting
uncoordinated data, the airwaves would be flooded with a plurality
of messages, which would result in a jamming of the radio waves, as
the radio bandwidth is limited.
[0012] As such, these vehicles would interfere with each other's
transmission and compete with each other for radio bandwidth for
transmission. Further, all messages would propagate in all
directions without any consideration of a desired transmission
direction.
[0013] Additionally, each vehicle would not match other vehicles'
network configurations.
[0014] The high mobility and lack of inherent relationships make a
priori configuration of vehicles into vehicle groups problematic
(e.g., a vehicle does not know anything beforehand about its
neighbor). All information that is necessary for setting up safety
communications must be exchanged in near real-time among vehicles,
and vehicles in the groups must configure themselves in near
real-time so that safety communication can take place. The high
mobility of uncoordinated vehicles implies frequent change of
neighbors or vehicle groups, and poses difficulties of using
support-servers (for mobility, address, name, media session) within
vehicle groups. These key differences make existing tactical ad-hoc
networking technologies not directly applicable to vehicle groups
for safety communications.
[0015] Using WiFi methods employed elsewhere, such as hotspots, are
impractical because of coverage, data traffic volume and latency
issues. A normal rush hour commute around a major city could yield
a vehicle density of as much as 600 vehicles per 1200-meter length
of a 3-lane highway. In addition, all these vehicles are moving
through individual coverage areas at a rate of 30 to 60 mph. Most
wireless systems are not equipped to handle such a large rate of
change in their network.
[0016] Specifically, as a vehicle enters the coverage area, it
would need to be identified and issued configuration instructions
by a wireless access point or router. When a vehicle leaves the
coverage area, the wireless access point or router would need to
update its records to remove the vehicle form its network. Thus,
the speed of a vehicle through a particular coverage area
determines how often updating information, e.g. handshaking, needs
to be broadcast by the wireless access point or router and
responded to by all of the vehicles in range. All of these vehicles
transmitting information at the same time could very easily
overwhelm the system in short order.
[0017] Several attempts have been made to establish a
vehicle-to-vehicle communication network. For example, FleetNet and
CarTalk2000 have both developed a vehicle-to-vehicle communication
network. Both of these systems use a GPS system in each vehicle for
location information and to route messages. FleetNet uses both
fixed and moving nodes as the infrastructure for "ad-hoc" networks.
The fixed node can act as a server router, a gateway router and a
client server router. This use of a plurality of fixed nodes causes
a significant financial cost and overhead to set up, maintain, and
manage the infrastructure. Additionally, the FleetNet system only
uses position based routing and location awareness to relay
messages. Specifically, as the backbone for their system, position
data plays a crucial role in the communication protocols
deployed.
[0018] CarTalk 2000 also uses a position-based protocol. Each
vehicle participating in the CarTalk2000-based inter-vehicle system
must be equipped with GPS devices to detect its current position at
any given time. Additionally, CarTalk2000 uses multiple different
routing protocols, such as Topological Information Routing,
Procedure Routing, and Reactive Routing--such as Ad-hoc On-demand
Distance-Vector Protocol, Dynamic Source Routing, Hybrid Routing,
etc. Each of these routing protocols uses a complex and distinct
set of protocol rules.
[0019] A major drawback of the CarTalk2000 system is the discovery
that neighboring nodes significantly increases bandwidth traffic.
Each node periodically sends a beacon to its neighboring cars
reporting its existence. In high traffic areas this would result in
constant beacon message collision.
[0020] However, these GPS networks have a significant drawback. In
a high-mobility vehicle environment, the GPS information quickly
becomes outdated. The exchange of constantly changing GPS
information among vehicles, in order to perform GPS-positional
routing, incurs too much protocol overhead and wireless bandwidth
waste. As a result, such GPS-positional routing technology cannot
achieve minimal communication latency or sustained multiple-hop
throughput.
[0021] Accordingly, there exists a need to create an ad-hoc network
capable of achieving the stringent VSC performance requirements
while achieving minimal communication latency or sustained
multiple-hop throughput without requiring excessive bandwidth and
significant protocol overhead.
BRIEF SUMMARY OF THE INVENTION
[0022] Accordingly, an object of the invention is to create
appropriate communication boundaries for a moving device to
moving-device communication by grouping a plurality of moving
devices into a management group, such as a Local Peer Group
("LPG"), to coordinate and relay message transmission and to
control the range and direction of the message propagation.
Additionally, an object of the present invention is to provide a
simple protocol for establishing and maintaining the Local Peer
Groups, dynamically assigning an identification and periodically
updating a relative order for the moving devices.
[0023] A method for organizing and maintaining an ad-hoc network
for communication between a plurality of moving devices is
disclosed. The method comprises the steps of grouping the plurality
of moving devices into at least one local peer group (LPG),
ordering the plurality of devices within each LPG based upon a
relative position of each of the plurality of devices within each
LPG and assigning a unique identifier for each of the plurality of
moving devices, where the unique identifier is based, in part on
the LPG in which the corresponding moving device is located.
[0024] There are two types of LPGs, a stationary LPG and a dynamic
LPG. A location and size of a stationary LPG are predefined and
programmed into memory of each moving device. A dynamic LPG is
formed based upon a clustering of one or more of the plurality of
moving devices. The network can include either the stationary LPG
and/or the dynamic LPG.
[0025] Each LPG can be divided into equivalent cells (EC) defined
by a group of moving devices that are within a one hop of each
other such that only one transmission of a message is needed to
reach any of the group of moving devices within the EC. Each EC is
controlled by an equivalent cell header (ECH).
[0026] The relative position of a moving device is updated to
account for reordering due to motion of the plurality of moving
devices. The ordering or reordering can be accomplished by creating
a position vector representing the relative position of each moving
device within each LPG.
[0027] A position vector is generated by initializing the position
vector, broadcasting the initialized position vector to another
moving device that is joining the LPG, comparing, by the another
moving device, its position with position information that is
included in the broadcast, inserting a position value of the
another moving device into the position vector based upon the
comparison, and broadcasting an updated position vector to all
other moving devices within the LPG.
[0028] Alternatively, the ordering and reordering of the moving
devices can be accomplished by broadcasting a message including a
first moving device's position, an indication of a intended message
direction, and a time of the broadcast, receiving the broadcast
message by a second moving device, estimating a displacement of the
first moving device based upon the received broadcast message,
calculating a current position for the first moving device based
upon the estimated displacement and the first moving device's
position, and comparing the calculated current position with a
position of the second moving device. A second moving device will
only relay or forward a message when the second moving device is
determined to be along the intended message direction.
[0029] The unique identifier for each moving device is LPG
specific. Therefore, the unique identifier is changed for a moving
device when the moving device changes LPGs. Additionally, a moving
device that is located near a border of two adjacent LPGs or within
a overlapping area of the adjacent LPGs is assigned two IP
addresses to allow for communication between the adjacent LPGs.
[0030] This unique identifier can be an IP address. The IP address
can be assigned based upon a predefined network prefix concatenated
with a unique LPG identification and a unique moving device
identification. The unique LPG identification and the unique moving
device identification can be calculated from a hash function.
Alternatively, the unique LPG information and the unique moving
device identification can be provided from an external wireless
device in communication with the plurality of moving devices.
[0031] Each of the plurality of moving devices can be classified
according to a type of moving device and the unique identifier can
be assigned based upon this classification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] These and other features, benefits, and advantages of the
present invention will become apparent by reference to the
following figures, with like reference numbers referring to like
structures across the views, wherein:
[0033] FIG. 1 illustrates an example of two local peer groups
according to the invention;
[0034] FIG. 2 illustrates a plurality of stationary LPGs according
to the invention;
[0035] FIG. 3 illustrates a plurality of dynamic LPGs according to
the invention;
[0036] FIG. 4 illustrates the method of ordering a LPG on an
"on-demand" basis according to an embodiment of the invention;
[0037] FIG. 5 illustrates an example of ordering the moving device
according to another embodiment of the invention;
[0038] FIG. 6 illustrates a method for ordering the moving devices
according to an another embodiment of the invention;
[0039] FIG. 7 illustrates a plurality of ECs within an LPG;
[0040] FIG. 8 depicts a wireless device that is attached or
embedded in a moving device according to the invention;
[0041] FIG. 9 illustrates an example of assigning an IP address
according to the above-identified embodiments;
[0042] FIG. 10 illustrates the format for an IP address according
to another embodiment of the invention;
[0043] FIGS. 11a and 11b illustrate two different IP address
formats used in the assignment of an IP address for a moving device
in a dynamic LPG;
[0044] FIGS. 12a, 12b and 12c depicts three different embodiments
for assigning a IP address for inter LPG communication according to
the invention;
[0045] FIGS. 13a and 13b illustrate two different formats for the
IP address for intra-LPG communication for a dynamic LPG;
[0046] FIGS. 14a and 14b illustrate two different formats for the
IP address for inter-LPG communication for a dynamic LPG.
DETAILED DESCRIPTION OF THE INVENTION
[0047] In accordance with the invention, nodes or moving devices
are organized into manageable groups. These groups are used to
coordinate transmission of data between the nodes. The groups are
built based upon the relative location of neighboring nodes or
based upon a fixed location. This grouping or Local Peer Group
("LPG") is the basis for routing radio signals within a single LPG,
as well as between LPGs. The radio signals include vehicle safety
applications and information applications.
[0048] The purpose of the LPGs is to build degrees of coordination
among neighboring nodes. These neighboring nodes are moving devices
with wireless communications capabilities. A moving wireless device
can be a PDA, laptop, cell phone, or a moving vehicle with a
wireless device either attached or embedded. Specifically, moving
devices include vehicles with associated communications devices,
which are installed in the vehicles, or independently brought into
the vehicles, as well as pedestrians with communication
devices.
[0049] There are two types of degrees of coordination; a first type
is a tight coordination of moving devices within an immediate
vicinity, which is used for intra-LPG communication for
near-instantaneous messaging. For example, sending an urgent
road-obstacle warning or another type of emergency or safety
message would be performed using the inter-LPG messaging. These
messages typically require a 100 msec latency.
[0050] A second type is a loose coordination, grouping moving
devices in a neighborhood. This type of coordination is used to
support inter-LPG communication among linked or interconnected
LPGs. For example, inter-LPG communication can be used for roadway
awareness application and for extending a driver's view.
[0051] LPG not only can support efficient and reliable
moving-device-to-moving-device communication, but also can support
moving-device-to-fixed-infrastructure communication so that moving
devices and roadway infrastructure can be integrated as a complete
communications network.
[0052] FIG. 1 illustrates two LPGs, the first LPG 100 includes four
nodes 110, 111, 112, 113, respectively. Each of these four nodes
110, 111, 112 and 113 can broadcast data to each other. The second
LPG 120 includes nodes 121, 122, 123, 124, 125 and 126,
respectively. Each of the nodes 121-126 can broadcast data to each
other. This type of transmission is an intra-LPG transmission and
occurs instantaneously. Nodes 110-113 in LPG 100 can broadcast data
to nodes 121-126 in LPG 120 by using inter-LPG communication. The
two LPGs, 100, 120 form the ad-hoc network 150.
[0053] There are two types of LPGs, stationary LPGs and dynamic
LPGs. A stationary LPG uses pre-assigned group location definitions
to partition moving devices. In contrast, a dynamic LPG coordinates
moving devices based on the (dynamic) radio coverage of the
neighboring moving devices for communication.
[0054] FIG. 2 illustrates a plurality of stationary LPGs (LPG 1-8)
200-207. Each LPG is defined by a specific location or area, i.e.,
if a wireless device or moving device is in area 1, the device is
LPG 1. If a wireless device or moving device is in area 2, the
device is LPG 2 and so on. The particular size of a stationary LPG
is a design choice, depending on various factors, e.g., range of
the radio antenna, communication range, number of moving devices,
topology of the land, the environmental conditions, traffic
patterns and population density. The location and size of the
stationary LPG is fixed, however, each stationary LPG might be of a
different size since traffic patterns and population (moving
devices) density is different in different places. Typically, the
LPG size should be larger than radio communication range to allow
for multi-hop communication. Additionally, to facilitate efficient
inter-LPG communication the stationary LPGs may also overlap the
area between adjacent LPGs. The overlapped area can have a flexible
size to adapt to variable situations, e.g. different moving devices
speeds.
[0055] According to one embodiment of the invention, the boundaries
for a stationary LPG is based upon a predefined area such as a zip
code or an area code. Typically, a zip code accounts for a
population density. The population density of an area is a good
indicator of a traffic pattern or the number of moving devices
within an area.
[0056] A stationary LPG based network architecture requires that
the moving device is equipped with a Global Position System (GPS)
or some other position information. This will allow the moving
device to identify or detect the stationary LPG to which the moving
device belongs. The moving devices will change stationary LPGs as
the moving devices change their position. Therefore, there is a
need for the moving device to periodically receive updated position
data. This period will depend on the speed or velocity of the
motion of the moving device. A moving device will include a
database of LPGs and their locations.
[0057] Stationary LPGs have a significant advantage of supporting
integration with wireless infrastructure to provide backbone access
or inter-LPG communication even when some LPGs are empty or do not
have many moving devices within the LPG.
[0058] Each stationary LPG is assigned a unique identifier to
facilitate communication. In one embodiment of the invention, the
unique identifier for the stationary LPG is assigned based upon the
zip code of the LPG. This method takes advantage of an existing zip
code database. Thus, there would be no need to create a new
identification number. Alternatively, in another embodiment, the
GPS coordinates of the stationary LPG can be used. Once again, the
method would take advantage of a predefined database. In another
embodiment, the state and city name can be used for the LPG's
unique identifier. Alternatively, any combination of the
above-identified embodiment can be used to assign an LPG unique
identifier. The LPG's unique identifier is used as part of the
moving device's unique identifier, as will be described later.
[0059] Since every stationary LPG area is well defined, formations
and naming the LPG is easier than the dynamic LPG. Additionally,
rules regarding merging and splitting an LPG are not a concern when
using a stationary LPG.
[0060] FIG. 3 illustrates a plurality of dynamic LPGs (LPG A-E)
300-304, respectively. As opposed to a stationary LPG, a dynamic
LPG is formed based upon the radio coverage of neighboring moving
devices so that a moving device can coordinate communications
without worrying about exact location of the moving device.
[0061] Since the dynamic LPG is formed based on radio coverage,
moving devices, within the LPG, can always communicate with each
other via single or multiple-hop transmission. The moving devices
are able to control the size of the dynamic LPG, in order to keep
the number of moving devices in each LPG reasonably small so that
the communication can be performed efficiently with low latency.
Additionally, in contrast with a stationary LPG, the dynamic LPG
ensures that communication is always possible within each LPG.
[0062] In one embodiment, an ad-hoc peer-to-peer network can be
created from one or more stationary LPG or one or more dynamic LPG.
In another embodiment, the ad-hoc peer-to-peer network can be
created from both stationary LPGs and dynamic LPGs as a hybrid LPG
network. A Hybrid LPG network combines the benefits of the
stationary LPG and dynamic LPG while removing the problems caused
by each taken separately.
[0063] One of the benefits of a stationary LPG is the ability to
easily group moving devices by area and to interact with
infrastructure. Additionally, the stationary LPG allows for simple
assignment of addressing or unique identifiers for each moving
device, as will be discussed in detail later. Further, every node
knows the whole network topology and structure. Therefore, a node
or moving device can be easily tracked.
[0064] There are several advantages of a dynamic LPG. One of the
advantages is that the dynamic does not need a priori
configuration, since the network is formed based upon a clustering
of nodes. Additionally, the dynamic LPG is also more flexible for
LPG forming, merging and separation and once formed all vehicles
can communicate at one time; therefore, communication between
neighboring moving devices is easier.
[0065] A drawback of the stationary LPG is that it requires a more
mature roadside wireless access points, roadside gateways, roadside
data storage (for deposit and retrieval), in contrast with the
dynamic LPG which needs none.
[0066] The hybrid approach would take advantage of the roadway
topology. Specifically, when infrastructure is not available, a
dynamic LPG is used to form the network. When infrastructure
becomes available in some area, a stationary LPG can be used to
form the network with dynamic LPGs and infrastructure.
[0067] For example, infrastructure, such as roadway infrastructure,
would enable roadway-vehicle communication or roadway-assisted
communication. This is particularly useful when using a stationary
LPG. Additionally, the roadway infrastructure will facilitate
Infrastructure-to-Vehicle communication. This type of communication
is important to distribute certain emergency information, such as
hidden driveway warning, electronic road signs, road surface
conditions, railroad crossing warning, route guidance and
navigation, highway merge assistance, intersection collision
warning, and work zone warning.
[0068] There are two main categories of LPGs: LPGs without ordering
and LPGs with relative ordering. In an LPG with relative ordering,
at least some of the moving devices are aware of the relative
location of neighboring moving devices. This relative ordering is
the basis for routing of messages within the LPG. The sense or
awareness of the relative ordering and relative direction of the
neighboring moving devices will enable an efficient routing of
messages in an LPG environment. This efficient routing is important
when the message is an emergency message in a roadway environment.
For example, a vehicle may designate a warning message as going to
the back of the LPG. Vehicles ahead of the sending vehicle in the
LPG do not need to receive or relay the message. Since the vehicle
will know the relative direction, the vehicle can direct the
message towards the proper direction thereby reducing the amount of
relay traffic and bandwidth used.
[0069] The sense or awareness of a direction can be derived from a
relative order of the moving devices. In one embodiment, the
relative ordering occurs on an "on-demand" basis. In another
embodiment, the relative ordering is maintained periodically.
[0070] FIG. 4 illustrates the method of ordering an LPG on an
"on-demand" basis, according to one embodiment of the invention.
The process begins at step 400. A first moving device broadcasts a
message that includes the moving device's GPS position, its current
velocity and timestamp along with an intended message direction. At
step 410, a second moving device receives this message. The second
moving device will estimate a current position for the first moving
device, at step 420. This is accomplished by estimating the first
moving device's current position based upon the first moving
device's likely displacement from its previous position, which is
known. The previous position is taken directly from the received
message. The likely displacement is calculated based upon an
estimated velocity and time difference. Since the received message
includes a timestamp, the second moving device calculates the
difference in time, i.e., from the timestamp to the time that the
message was received. This would require that the moving devices
have a synchronization in time for both the clocks and GPS
information, i.e., GPS devices are synchronized. The estimated
velocity can be calculated in several different manners. In one
embodiment, the (instantaneous) velocity of the first moving-device
is included in the message sent by the first moving-device. This
velocity can be used by the second moving device as the estimate of
the first moving-device's current velocity. In another embodiment,
the second moving device can use its own velocity as the velocity
for the first moving device. Alternatively, a predetermined
estimated velocity can be used. The predetermined estimated
velocity will be pre-stored in the moving device's memory in a
database that can vary based upon the speed limit, time of day,
location, weather conditions, and topology. The second moving
device will multiply the estimated velocity with the difference in
time to obtain the likely displacement. This value is the likely
displacement from the previous position and is used to adjust the
first moving device's previous position to obtain the estimated
position of the first moving device.
[0071] In one embodiment of the invention, the displacement of the
first moving-device has an orientation component. In this
embodiment, the estimated displacement accounts for a change in
orientation. The change in distance will be added to the previous
location in the direction of the traveling of the first
moving-device. In one embodiment, the first moving-device may
include its GPS orientation (e.g., NW, SE35.degree.) in its message
(along with its position, timestamp, etc.), and this orientation
information is used by the second moving-device to estimate the
exact displacement. Alternatively, in another embodiment, the
second moving-device may estimate the orientation of the first
moving-device (without the first moving-device sending any
orientation information) by taking advantage of the local topology
information, i.e., both moving-devices may be traveling along the
same roadway. Therefore, the second moving-device can add the
calculated displacement to the previous position (of the first
moving-device) in the direction that the second moving-device is
moving.
[0072] At step 430, the second moving device will compare the
calculated estimated position of the first moving device with its
current position to determine the relative ordering of the two
moving devices.
[0073] The second moving device will only relay or forward the
message when the second moving device is determined to be along the
intended message direction. A moving device is along the intended
message direction if its position and orientation is between a
sending moving device and the receiving moving device.
Specifically, the second moving device will use the calculated
relative order or position to determine if the second moving device
is along the intended path.
[0074] In one embodiment, the orientation information is used to
determine if the second moving device is along the intended path.
This orientation information is used by the second moving device to
derive the estimated position of the first moving device as
described above. Once the relative ordering between the two moving
devices is determined as described above, the second moving device
can determine if it is on the path of first moving-device's
intended message transmission by using the orientation of the first
moving device, that is included in the message from the first
moving device and its own orientation. For example, when both
moving devices have similar orientation (i.e., traveling along the
same roadway) and the second moving device is ahead of the first
moving device (determined by their relative ordering), the second
moving device will forward the message (of the first moving device)
if the intended message direction is along the same orientation,
whereas the second moving device will not forward the message if
the intended message direction is of the opposite orientation. In
another embodiment, where the first moving device does not send its
orientation information in the message, the second moving device
may estimate the orientation of the first moving device, as
described above, e.g., estimation of displacement to the previous
position. Once the orientation and the relative ordering of the two
moving devices are known, the second moving device can determine if
it is along the path of the first device's intended message
transmission in an analogous manner, as described above.
[0075] If the second moving device is not in the path, the message
will not be forward. Ordering the moving devices, according to this
embodiment, has an advantage that the bandwidth is not flooded with
ordering requests when the ordering of the moving devices is not
important.
[0076] In another embodiment of the invention, the relative order
of the moving devices is periodically updated using a position
vector. FIG. 5 illustrates an example of ordering an LPG using this
method. FIG. 5 depicts an LPG 500 with an LPG position vector V
510. The LPG is mapped into a one-dimensional array or vector V
510. Each moving device of the LPG 500 will have a vector ID, which
is just its position index of V. As depicted in FIG. 5, the vector
V 510 represents a position order of the moving devices. In FIG. 5
there are six different relative orders 1-6. The arrow illustrates
the direction of the motion for the moving devices, e.g., traffic
flow.
[0077] The position vector V 510 allows a moving device to control
the direction of information transmission. In particular,
information can be routed in the peer group using the position
vector V 510. For example, if a sending moving device with index 3
as depicted in FIG. 5, indicates that its message is meant for
moving devices with indices that are smaller than 3, only the
moving devices that have index j<3 will relay the message. This
will be accomplished by indicating that the message is meant for
vehicles with indices smaller than j. The relaying will continue
until the message reaches the backend boundary node of the LPG or
the message has reached the maximum number of hops. Information
propagation in the forward direction can be achieved in an
analogous fashion.
[0078] Additionally, by using the position vector V 510 a routing
priority can also be facilitated. The MAC layer can develop an
access priority based upon this position vector 510. In general, in
the network, a higher access priority will be given to moving
devices with lower position indices (the ones at the front part of
the LPG) since moving devices in front are more likely to observe
warning events and deserve to use the wireless channel at higher
priority.
[0079] FIG. 6 illustrates a method of creating the position vector
V 510 according to an embodiment of the invention. The process
begins at step 600 by initializing the position index I when a
moving device, for example node N, joins an LPG. Node N makes
contact with at least one other moving device already in the LPG,
for example, node L, by receiving a message from the other moving
devices. Node N learns of the position of node L based upon the
received message that includes node L's GPS position, step 602.
Node N compares the received position information with its own GPS
position and inserts itself into the vector V 510 based upon the
comparison. Node N then transmits the new position vector V 510 to
the other moving devices within the LPG, e.g., to node L. For
example, if node N is ahead of node L, and node L was the front-end
position with an index of N, then node N assigns itself a value of
N-1 as its position index and becomes the new front-end of the LPG,
at step 605. On the other hand, if node N is behind node L and L is
the back-end position with an index of n, node N will assign itself
a value of N+1 as its position index and takes over as the back end
position, at step 610.
[0080] If the moving device, e.g., node L, with index of n is
neither the front-end or back-end, node N is joining in the middle
of the LPG. Node N will then insert itself into the position V by
comparing the GPS with node L, step 615, as set forth above and
then trigger any of the indices of all of the moving devices behind
the insertion point, at step 620. The other nodes behind the
insertion point will then update their position index based upon
the change in their GPS position.
[0081] Alternatively, instead of automatically triggering the
update of the other moving devices upon insertion of the new node
or moving device, the new moving device is assigned the index n+1,
and all moving devices with indices larger than n will increment
their indices by 1.
[0082] Another alternative to automatically updating or
incrementing the position vector V 510 is to increment the other
moving devices within a predetermined position interval. This would
reduce the frequency of index updates. A node N joining in the
middle is assigned an index taken from an interval of values,
between n and n+K, without the need to increment the indices of
moving devices with positions higher than n+K. Only moving devices
within this interval (n and n+k) would need to update their
position index.
[0083] Additionally, the position vector V 510 can be updated to
maintain the relative order of moving devices within the LPG, i.e.,
once the moving device has joined the LPG. Each moving device can
update its position index periodically. The position index (i) of
moving devices inside the LPG may be maintained, so that the
position vector V 510 includes the current relative positions of
the moving devices in the LPG. In particular, the position index
can be updated when moving devices change relative positions caused
by moving devices passing each other. The position index of the
moving devices is swapped when two moving devices swap their
relative positions. For example, at a periodic interval, moving
devices exchange or broadcast its GPS position and swap position
indices if their relative positions have swapped. The period can be
adjusted based upon the type of network, topology, time of day,
traffic pattern and type of message, or location of the LPG, e.g.,
more frequent updates around an exit/on ramps or intersections, and
less frequent updates when the moving devices are between the
exit/on ramps or intersections. The overhead to maintain ordering
consistency can be reduced by increasing the update interval.
[0084] However, the exchange of GPS or position information has its
drawbacks particularly in a roadway environment. Specifically, the
number of moving devices in an LPG might cause heavy amount of GPS
coordinates being communicated constantly (trying to keep up the
change in relative positions). Additionally, there is a potential
that the error of the GPS coordinates may be on the same order of
the moving devices separation distance, so the resulting position
calculations may not be accurate enough. Additionally, the above
method requires a significant amount of the calculation and, in
general, the GPS information is outdated when other moving devices
receive them.
[0085] In another embodiment, the relative order of the moving
device can be determined by using messages and position vectors,
without using GPS information. As stated above, maintaining the
ordering using a GPS approach may incur a significant overhead,
especially where the number of moving devices is large. In this
embodiment, an LPG is divided into several smaller groups or
equivalent cells (EC). Each EC is assigned one position index. An
EC is a group of neighboring moving devices that are within the
same radio coverage. An EC is a segment of the LPG that has the
same vector index for all of the moving devices within the EC and a
single message transmission can be received by all of the moving
devices within the EC.
[0086] The EC is formed to link with other ECs to disseminate
information using the ECs as the basic units. FIG. 7 illustrates a
plurality of ECs (EC1-5) 701-705 within a LPG 700. The ECs 701-705
can be arranged within the LPG 700 to overlap radio coverage. In
the network depicted in FIG. 7, the relative ordering of the LPG is
maintained among ECs, to reduce the overhead. Additionally, a
message is relayed once per EC, to improve bandwidth
efficiency.
[0087] For example, moving devices within an EC can be reached with
a single packet transmission. Each EC is organized such that some
moving devices in the EC can relay a packet, if needed. The ECs can
be ordered within the LPG, so that messages can hop along the ECs.
Specifically, if a moving device in EC3 703 wants to send a packet,
that moving device can transmit the packet (once) to the
neighboring EC2 702 and EC4 704, which ensures that all moving
devices in EC2 702 and EC4 704 are reached. This packet may be
relayed by EC2 702 and EC4 704 onto their respective neighbors, one
packet per EC. This type of neighborhood-to-neighborhood routing,
one packet per neighborhood, can minimize packet transmissions
within LPG.
[0088] An EC is maintained and controlled by one equivalent cell
header (ECH). Each ECH 711-715 is linked with its neighboring ECHs
so that all ECHs 711-715 in an LPG, whether directly or indirectly,
are serially linked. The ECHs 711-715 are connected in order of
radio hop counts and represent the forwarding nodes for the LPG.
Only ECHs 711-715 are responsible for relaying messages, which
minimizes unnecessary traffic.
[0089] In this embodiment, the ECHs order themselves and maintain
their order to accomplish the ordering for the LPG. Each ECH
announces its presence in the LPG by broadcasting a predefined
message. This message is broadcast periodically and advertises a
list of linked ECHs, i.e., comprises one-hop, two-hop, three-hop in
a position order relative to the broadcaster's perspective. The
list is received by other ECHs, which cause the other ECHs to
update their list and store the list in memory. Non-ECHs 720 also
update their list. This allows that all ECHs lists are consistent
with each other. The list represents the relative order for each
ECH. This facilitates a determination of the direction of motion
and direction of the transmission.
[0090] In one embodiment, the broadcast message contains an ID of
the source originating the message, a first list of ECH nodes that
are visible to the source along a first communication path of the
orderly connected ECs, and optionally a second list for a second
communication path of the orderly connected ECs. Additional lists
may be provided, wherein each Linked ECH (LECH) list contains ECH
IDs for all ECH nodes encountered along one branch, or
communication path, of the orderly connected ECs, with the source
ECH as the epicenter.
[0091] For example, each ECH knows the relative position of its
direct neighboring ECHs, i.e., the ECH for EC 3 703 knows that the
ECH for EC 2 702 and EC 4 704 are in a different direction based
upon the list or vector broadcast by the ECH for EC 2 702 and EC 4
704, respectively. The ECH for EC 3 703 will broadcast its message
containing this information. Further, the ECH for EC 2 702 knows
that the ECH for EC 1 701 and EC 3 703 are in a different direction
based upon the list or vector broadcast by the ECH for EC 1 702 and
EC 3 703, respectively. This information will be combined and
stored as one list that each ECH maintains.
[0092] Accordingly, by using the relative order for the ECHs, the
message can be routed in the proper direction without any GPS
information.
[0093] Alternately, in another embodiment, all moving devices are
equipped with directional antenna in key directions (e.g., front,
back, left, and right, plus possible diagonals) and are able to
sense the presence of other moving devices in these directions. Any
moving device can indicate a message as going toward the back of
the peer group, sends a message only on its back-pointing
directional antenna, and moving devices receiving this message may
relay only on their back-pointing antenna. This approach provides
the basic direction sense, but does not provide relative positions
among moving devices.
[0094] The moving device according to the invention includes a
wireless device that is attached to, embedded in or used in
combination with the moving device. FIG. 8 depicts a wireless
device according to the invention. The wireless device according to
the invention includes a computing device 800 having a broadcasting
means 802, such as a wireless transceiver, for providing wireless
communication between nodes in a radio coverage range.
Additionally, a controlling means 804, e.g., microcontroller,
microprocessor, etc., is configured for receiving signals from
other nodes through the broadcasting means 802 and transmitting
signals to other nodes through the broadcasting means 802. The
controlling means 804 also provides operational control by
executing the instructions. A storage means 806 is disposed within
the computing device 800 and in operational communication with the
controlling means 804. The storage means 806 may be memory modules,
removable media, a combination of multiple storage devices, etc.,
and is dimensioned to store the processor-executable instructions
necessary for the performance of the protocols of the described
embodiments. Further, a timing means 808 is provided either as a
separate component or via a function of the controlling means 804.
The timing means 808 provides the time interval tracking necessary
for each of the timers referred to in the described embodiments. An
energizing means 810, such as a power supply, is electrically
connected to all the components of the computing device 800 for
providing operational power to the components as necessary. The
wireless device further includes an internal clock that maintains a
clock for the wireless device and is used as the timestamp for all
messages. Additionally, the wireless device includes an address
assignment means 812 and a network interface means 814.
Alternatively, the address assignment means 812 can be part of the
controlling means 804.
[0095] The processor-executable instructions for performing the
described embodiments may be embedded in the storage means 806 in a
form such as an EPROM, Flash memory or other such non-volatile
storage. Additionally, the processor-executable instructions may be
stored on a computer readable media such as an optical or magnetic
medium, or may be downloadable over a network (e.g., Internet).
Preferably, a user, as necessary, can periodically update the
processor-executable instructions in order to provide additional
enhancements to the system as they become available.
[0096] Each moving device will be assigned a unique identifier to
facilitate the transmission and reception of messages over the
ad-hoc network. The unique identifier can be any number that is
uniquely assigned to the moving devices so that no moving device
within an LPG is assigned the same unique identifier. This
identifier must be assigned quickly to support immediate
communication, if necessary. As stated above, the unique identifier
can be any unique number or address that facilitates communication,
such as a MAC address, VIN number, or IP address; however, for
purposes of an example, assignment of an IP address will be
discussed. Typically, a moving device will have at least one IP
address. However, in one embodiment, two IP addresses will be
assigned to the moving device, to support both intra-LPG
communication and inter-LPG communications.
[0097] In the preferred embodiment, the IP address will be based
upon a special network prefix, the LPG unique identifier and a
moving device's identification. Specifically, an IP address can be
assigned based upon a predefined network prefix concatenated with a
unique number that corresponds to a specific moving device, where
the unique number is based upon the LPG that the moving device is
in and a number corresponding to the moving device.
[0098] While similar assignment techniques for assigning addresses
for both a stationary LPG and a dynamic LPG can be used, the
assignment of addresses will be described separately for each type
of LPG.
[0099] For a stationary LPG, in one embodiment of the invention,
the IP address can be a standard network prefix and LPG ID
concatenated with a hash value of the MAC address and VIN number or
a time. The usage of a hash function is particularly important when
there is a limitation on the address space, i.e., IPv4. According
to this embodiment, the moving device will assign its own IP
address.
[0100] In an ideal situation, the LPG will only have N moving
devices, where N is the maximum address space, as the limitation in
address space would be rendered moot. This will allow for a simple
assignment of a private class for each LPG. Each moving device
within the LPG will have a different lower portion of the IP
address. This IP address can be reused in different LPGs as long as
they are not near each other.
[0101] However, typically a LPG might be larger than N moving
devices. Accordingly, a predefined hash function will be stored in
the memory section of the moving device. The address assignment
means 812 will access this predefined hash function from memory to
assign the lower portion of the IP address. The hash function will
translate a plurality of input numbers into an M-bit number, where
M is the maximum number of bits in the lower portion of the IP
address. The plurality of input numbers can include the VIN number,
MAC address and the time that the moving device joined the LPG.
[0102] The standard network prefix is the upper portion of the IP
address. The standard network prefix is also stored in memory.
Furthermore, the IP address is LPG specific. A portion of the IP
address will be used to identify the specific LPG where the moving
device is located. A database of LPG locations and associated LPG
ID is also stored in memory. When a moving device enters a new LPG
area, the moving device will have to change its IP address to
reflect the specific IP address that is associated with the LPG. An
advantage of a stationary LPG is that the LPG locations are fixed
and well defined. This allows for the naming of the LPG ID to be
simple.
[0103] Alternatively, in another embodiment of the invention, a
portion of the IP address or the entire address can be assigned by
a stationary wireless device within the LPG. For example, a portion
of the IP address can represent a sequence or order that the moving
device entered the LPG. This would require an external wireless
device transmitting a sequence number to the entering moving
device. A connection can be established through a type of
query-relay-reply operation. When a new moving device enters an
LPG, it will make a query (through broadcast). The query is relayed
by other moving devices in the LPG to a predetermined external
wireless device. The external wireless device can include a
roadside gateway device, another moving device such as a leader, or
the first moving device within the LPG. The external wireless
device will act as a DHCP server.
[0104] The external wireless device will generate a sequence number
or IP address and respond to the query by sending a reply. This
sequence number will be used as the lower portion of the IP address
instead of the hash value. The sequence number will be concatenated
with the upper portion of the IP address, as set forth above. Using
this method, there is a potential that the IP address will
continuously change as the sequence changed as a result of the
constant motion of the moving devices. Alternatively, the entire
address can be transmitted to a moving device that enters the
LPG.
[0105] In another embodiment of the invention, if the IP protocol
supports a wide range of IP addresses, the IP address can be the
standard network identifier concatenated with the entire MAC
address or VIN number. For example, using the IPv6 protocol, there
is a significant amount of space to assign a unique address for
each moving device without a need for a hash function. The upper 64
bits of the IP address can be dedicated to the LPG ID and the lower
EUI 64 bits can be calculated directly from the MAC address or VIN
number.
[0106] The upper portion of the IP address can include the standard
network prefix and the unique LPG ID. The lower EUI portion will
include each of the MAC address or VIN number.
[0107] FIG. 9 illustrates an example of assigning an IP address
according to IPv4 protocol. FIG. 9 depicts four overlapping LPGs,
LPG1 901, LPG2 902, LPG3 903, and LPG4 904. The first two triplets
905 in the IP address represent that standard network prefix
"192.168". The standard network prefix "192.168" is the same for
all LPGs within the network. The third triplet 906 is the LPG ID
and is LPG specific. As illustrated in FIG. 9, LPG1 901, LPG2 902,
LPG3 903, and LPG4 904 have a value of 1, 2, 3, 4 in the third
triplet 906, respectively. The fourth triplet 907 represents the
individual moving device's identification. This number will vary
based upon the moving device. This number can be assigned using any
one of the embodiments described above.
[0108] FIG. 10 illustrates an exemplary format for an IP address
for the IPV6 protocol. For illustrative purposes the same LPG
reference numbers will be used for FIG. 10 as was used for FIG. 9.
The upper portion 1000 is depicted to be 64 bits and represents the
LPG ID and the lower portion 1001 is also 64 bits and represents
the moving device's identification (EUI). Both the upper and lower
portions 1000 and 1001 are different for each stationary LPG.
[0109] Additionally, as stated above, there might be some
overlapping area between stationary LPGs to let moving devices
change their LPG smoothly and to support easy inter-LPG
communication. In the preferred embodiment, in overlapped areas,
each moving device will have two IP addresses to allow for access
to both LPGs. As a moving device approaches the overlapping area,
the address assignment means 812 will assign a second IP address to
the moving device. Specifically, the moving device will compare the
position of the overlapping area, which is stored in memory, with
its current position to determine if the moving device is located
with the overlapping or boundary area. A wireless device has a
network interface means 814 (i.e., 802.11 card). Many logical
interfaces can be supported by the physical wireless interface.
Each logical interface has one IP address. Each network interface
means 814, therefore, can have more than one IP address. Each IP
address can be assigned according any of the above-identified
embodiments.
[0110] While similar techniques for assigning IP addresses for a
stationary LPG can be utilized, assigning IP addresses for a
dynamic LPG is more dynamic in nature. This is because the LPG's
location is no longer fixed. Additionally, the LPG ID is not fixed
and changes continuously. Furthermore, the assignment of an IP
address to inter-LPG communication is different for a dynamic
LPG.
[0111] For intra-LPG IP address assignment for a dynamic LPG, the
techniques are fairly similar to those used for assigning an IP
address for a stationary LPG for the IPv4. FIGS. 11a and 11b
illustrate two different examples of IP address formats for the
IPv4 protocol. In both formats, the upper portion, i.e., first two
triplets 1100 of the IP address is determined by a standard network
prefix, e.g., 192.168, 10.0. and 172.12. In one embodiment, the
standard network prefixes will be private addresses. The standard
network prefix will be the first two sets of triplets of the
address.
[0112] The third triplet 1101 is the LPG ID. In one embodiment, the
LPG ID is randomly generated. The fourth triplet is the moving
devices identification. This identification number can be assigned
based upon either a hash function of the VIN or MAC address 1102a,
as illustrated in FIG. 11a or a sequence that the moving device
entered the LPG 1102b, as illustrated in FIG. 11b. The hash
function and sequencing has been described above regarding the
stationary IP address assignment and will not be described
further.
[0113] This IP address will allow for communication within the LPG,
i.e., intra-LPG; however, a separate IP address must be assigned to
the moving devices for inter-LPG communication. This will be a
public IP address. This public IP address can be assigned by an
external wireless device, acting as a DHCP server or another moving
device acting as the DHCP. This address assignment follows the DHCP
protocol between a moving-device (which acts as the representative
of the LPG) and the external device (which acts as the DHCP
server).
[0114] In one embodiment of the invention, one moving device within
the LPG is assigned a public IP address for inter-LPG communication
using the IPv4 protocol. As depicted in FIG. 12a, one node 1202 is
assigned a public IP address IPA 1204. This node 1202 can be the
first moving device within the LPG, a moving device that is
selected to be a leader, or based upon another predefined selection
criterion. Alternatively, the selection can be random. The
remaining nodes 1201 will not have a public IP address IPA 1204
assigned.
[0115] In another embodiment, each moving device within a given LPG
will be assigned a different IP address. As depicted in FIG. 12b,
the LPG 1200 has six nodes 1201. Each node 1201 will be assigned a
different IP address IPA-IPF 1204-1209.
[0116] In a third embodiment, only one global public IP address is
assigned for all moving devices in an LPG. As depicted in FIG. 12c,
each moving device or node 1201 within LPG 1200 is assigned the
same public IP address 1204. This public IP address 1204 is
globally recognizable by others for communication over the
Internet. For example, a public IP address could be 239.5.5.5
[0117] For the IPv6 protocol, there are two different methods for
assigning an IP address for intra-LPG communication. Wireless
devices, using the IPv6 protocol, are capable of two auto
configuration functions: link local address and router
advertisement address.
[0118] FIGS. 13a and 13b illustrate the two different examples of
formats for the IP address for intra-LPG communication. As depicted
in FIG. 13a, the first approach uses a link local address 1300,
e.g., fe80. The link local address 1300 will be the upper portion
of the IP address. The lower portion, the EUI 1302, which is 64
bits is calculated from the MAC address and/or VIN number. However,
the link local address approach is only valid within the LPG and
requires a second additional address for inter-LPG
communication.
[0119] The second approach is to use site local-like approach or
the router advertisement address as depicted in FIG. 13b. The
network will include a predefined moving device prefix 1301
dedicated for a moving device network or vehicle network. This
moving device prefix 1301 will be combined with an LPG ID to be the
upper 64 bits, as represented in FIG. 13a as "XXXX" 1303. The lower
64 bits, the EUI64 1302, will be the same as in FIG. 13a.
Therefore, the EUI64 number will be the same for both formats, and
the difference is the upper portion of the ID address.
[0120] In both formats the LPG ID is used for a potion of the
address. LPG ID must be unique for each LPG. According to an
embodiment of the invention, the LPG ID can either be a randomly
assigned number or predefined by a hash function. The hash function
can account for the location of the LPG, if available, the MAC
address of the first moving device within the LPG or the VIN number
of the first moving device within the LPG.
[0121] For Inter-LPG address assignment, in one embodiment, an
external wireless device is used to assign a portion of the IP
address. The external wireless device can be any device such as a
roadside gateway or a boundary router broadcasting its address
range and prefix to LPGs. The network prefix can be obtained from
those gateways' (routers) advertisement. The received network
prefix 1400 will be used for the upper portion of the IP address,
e.g. a global directory for the IP address. The lower portion of
the IP address can be the same EUI64 1302 number as used for the
intra-LPG communication IP address.
[0122] In another embodiment, a predefined vehicle or moving device
prefix 1301 will be created and installed in the memory section of
each moving device. This moving device prefix 1301 will be combined
with a LPG ID 1303 to be the upper 64 bits. LPG ID must be unique
for each LPG. According to an embodiment of the invention, the LPG
ID can either be a randomly assigned number or predefined by a hash
function. The hash function can account for the location of the
LPG, if available, the MAC address of the first moving device
within the LPG or the VIN number of the first moving device within
the LPG. The lower portion of the IP address can be the same EUI64
1302 number as used for the intra-LPG communication IP address.
[0123] In one embodiment, any moving device can be assigned any IP
address. In another embodiment, a specific IP address can be
reserved for different classes of moving devices. For example, an
emergency vehicle can be assigned a specific range of IP addresses.
An IP address within this range will be saved for emergency
vehicles such as ambulances, polices cars, and fire trucks. An
external wireless device or gateway will be aware of special moving
devices and have a list of the special moving devices or
classifications of moving devices stored in memory. These special
vehicles must use a special query for requesting an IP address.
[0124] This would facilitate priority messages from emergency
vehicles. In other words, all messages originating from a specific
range of IP addresses would have the highest priority for
transmission.
[0125] The invention has been described herein with reference to a
particular exemplary embodiment. Certain alterations and
modifications may be apparent to those skilled in the art, without
departing from the scope of the invention. The exemplary
embodiments are meant to be illustrative, not limiting of the scope
of the invention, which is defined by the appended claims.
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